Paper – material which is the integral partner in life of mankind. The history of the paper contains many centuries. It was invented in China. At the moment there are several types of technologies of its production.
History of the paper
The first mentions of the invention of material for writing of texts meet in ancient Chinese sources. Official date of the first emergence of the first standard sheet 105 is considered BC, and this event contacts a name of the dignitary from China Cai Longya. The similarity of paper was used also to a novelty, but made this material of strongly steamed out silk or hemp. Cai Lun made several experiments thanks to what the unique recipe appeared. In one capacity fabric pieces, ashes, fibers of a mulberry and a stump were mixed. All ingredients should be mixed carefully and an even layer to lay out in special forms. Then preparation dried under sunshine and was pressed by means of stones. As a result thin sheets turned out.
It should be noted that exact date of an invention of paper is unknown. Archeologists found pieces of material, similar to paper, during excavation in Egypt. And date of finds belongs to the 300th years BC.
Modern production
At the moment paper is made at the plants equipped with the special equipment. There are three options of production – from wood or chemical cellulose and also from waste paper. Wood cellulose is received from bark of birches, an eucalyptus, a poplar, a pine or a fir-tree. Material is carefully crushed by means of the special equipment, and then mixes up with a certain amount of water. Further mix gets on machines which make thin sheets of paper by pressing and alignment. Material of such quality is generally used for printing of newspapers or printing editions of rather low cost. Paper has a yellowish shade and differs in not too high rates of durability. Chemical cellulose is used for production of more quality white paper. Process of production of such material happens also in several stages. Bark of trees is crushed in a small crumb which is carefully sifted. Then sawdust throughout certain time is cooked in huge coppers. Only after that the received weight mixes up with special acid. For obtaining more dense paper quite often to bulk mix the crushed waste paper. The final stage depends on requirements. For example, if glossy paper is necessary, then add pitch to mix. If paper of the increased durability is necessary, then glue becomes additional ingredient. After necessary additives, mix goes under a press and is carefully dried up. From waste paper to make paper much easier. "Old" paper is purified from paint which is used for drawing images and the text. Then material carefully is crushed and exposed to special processing thanks to what the mix reminding semolina porridge is formed. Weight goes to the rotating tapes and is exposed to pressing, previously sometimes add wood bark to structure. As a result of such process, white paper which is cut then on sheets and is formed in separate blocks turns out. For production of color paper dyes of a certain color are added to standard mixes. Sheets which have to become velvet, brilliant or relief are exposed to additional processing.